Because of the characteristics of wind resource distribution and development status of power grid in China, “Three Norths” (northwest China, north China and northeast China) that have rich wind resources in China have the characteristics of large-scale centralized development and as wind power plants are generally the terminal of an electric power system, local load is relatively low and power grid is weak, wind power cannot be totally consumed locally, so that it needs to be delivered to other places. However, due to the randomness and volatility of wind power, it is difficult to control wind power delivery. In addition, the annual utilization hours are low, economical efficiency of independent long-distance transmission is poor and volatility of wind power transmitting power is high. All these problems have seriously influenced safe and stable operation of the electric power system.
Considering that the regions with rich wind resources are also of rich coal resources, if the wind power and thermal power are “bundled” together for delivery, through coordinated control of wind power and thermal power, it not only can guarantee “bundling” delivery cross-section not exceed the stability limit, reduce fluctuations of the line power while fully using wind resources and taking full advantage of transmission channel, but also can improve reserve capacity of the system. Further, it is also beneficial to the security and stability of the system and significantly decreases power supply cost of the receiving end as well.
At present, wind power and thermal power “bundling” coordinated delivery has been widely used in China. A lot of researches have been made on “bundling” control strategy, objectives of which mainly focus on optimizing generation scheduling of a thermal power generating unit, reducing fluctuating power of a transmission line, improving wind power consumption capacity, solving the problems as thermal reserve capacity of a grid reduces and optimizing wind-thermal structural proportion that are generated during wind power and thermal power “bundling” coordinated delivery. However, few researches have been made in optimal control of wind-thermal power coordination.